HP Remote Assistant User's Guide

2 Hardware Installation and Configuration
30
Configuring a Null Modem Cable
In a direct connection, the null modem cable has key signals crossed to make the
terminal appear as if it were a modem. The figure below illustrates the cable
configuration required for making a direct connection to the HP Remote Assistant.
Terminal or PC HP Remote Assistant
EISA Card
DCD
RX
TX
DTR
GND
DSR
RTS
CTS
RI
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
DCD
RX
TX
DTR
GND
DSR
RTS
CTS
RI
Male MaleFemale Female
Figure 2-16. Null Modem Cable Configuration
It is possible to create a minimal three-wire direct connection using the cable
configuration illustrated in the figure below.
Terminal or PC HP Remote Assistant
EISA Card
DCD
RX
TX
DTR
GND
DSR
RTS
CTS
RI
1
2
3
4
5
6
7
8
9
1
2
3
4
5
6
7
8
9
DCD
RX
TX
DTR
GND
DSR
RTS
CTS
RI
Male MaleFemale Female
Figure 2-17. Minimal Null Modem Cable Configuration
When the HP Remote Assistant enables its port by asserting DTR, it automatically
recognizes that DCD, DSR, and CTS are asserted and establishes the connection.